Brown clouds of pollution: Karachi among Asian cities getting dimmer natural light

Vast "brown clouds" of pollution are making Asian cities darker, melting Himalayan glaciers and intensifying regional monsoons, a UN report said on Thursday.
A team of scientists highlighted the three effects after studying a "more than 3-kilometre-thick layer of soot and other man-made particles that stretches from the Arabian Peninsula to China and the western Pacific Ocean", the United Nations Environment Programme said.
The "atmospheric brown clouds" result from the burning of fossil fuels and biomass, and in some areas also worsen the impact of climate change caused by greenhouse gas emissions, the UNEP report said.
At least 13 major cities in Asia and other regions, including Beijing and New Delhi, get less sunlight because of the pollution, while its effects on air quality and agriculture in Asia pose "increasing risks to human health and food production for three billion people."
The other darker cities identified were Bangkok, Cairo, Dhaka, Karachi, Kolkata, Lagos, Mumbai, Seoul, Shanghai, Shenzhen and Teheran. The natural light was between 10 per cent and 25 per cent dimmer in cities such as Karachi, Beijing, Shanghai and New Delhi, the report said.
India as a whole had become darker by about 2 per cent per decade between 1960 and 2000, while China had lost its natural light by about 3 per cent to 4 per cent per decade from the 1950s to the 1990s. "One of UNEP's central mandates is science-based early warning of serious and significant environmental challenges," UNEP Executive Director Achim Steiner said in a statement. "I expect the atmospheric brown cloud (ABC) to be now firmly on the international community's radar as a result of today's report," Steiner said.
Scientists from the United States, Europe, China, India and other Asian nations had studied the formation of clouds of pollutants since 2002, when their initial findings were met with scepticism, said lead scientist Veerabhadran Ramanathan of the US-based Scripps Institution of Oceanography.